112 Hum

Dale Tiemessen · From: New Hampton,Ia. U.S.A.

Myself and a friend are both having a problem with a hum in our Peavey 112 amps. Seems like the only to get it to a level where I can stand it is to turn the post gain to almost zero.

Bud Angelotti · From: Larryville, NJ, USA

Are you both having problems with the amps in the same building? Might be a problem with lighting or interference in THAT place.

Dale Tiemessen · From: New Hampton,Ia. U.S.A.

No.Differend buildings,many times.Always the same hum.

Jack Stoner · From: Kansas City, MO

Is the reverb causing the hum? Turn the Reverb knob to zero and see if that is the cause.

Lefty Schrage · From: West Union, Iowa, USA

Dale, I have a hum problem with both of my 112's and I've tried the amps in different places in the house, outside the house, in the garage, etc. I also turned off the verb and it made no difference. A couple of years ago, I sent the chassis for one amp to Peavey and they returned it saying their "techs" checked it and everything was up to specs...but it still had the hum. I, too, would be interested in knowing how many other steelers are experiencing the same problem.

Clyde Mattocks · From: Kinston, North Carolina, USA

Mine hums if I use the internal reverb, which I don't. I use an outboard Lexicon unit. If I turn the amp up high, there is some hum, which is true of most amps. However, if I have to turn it that high, I am going to be playing so loud, the hum is masked. See how much hum it has with nothing plugged in. You may be getting hum from something else in the signal path or just plain old single coil pickup hum.
_________________
LeGrande II, Nash. 112, Fender Twin Tone Master, Session 400, Harlow Dobro, R.Q.Jones Dobro

Lane Gray · From: Topeka, KS

Stupid question. Have you tried a power conditioner? Replacing cables?
_________________
2 pedal steels, a lapStrat, and an 8-string Dobro (and 3 ukes)
More amps than guitars, and not many effects

Mitch Druckman · From: Arizona, USA

I also have a hum problem with my Nashville 112. I thought it might be a problem with my house power, but I don't have the problem with any of my other amps.

I haven't taken the time to troubleshoot it yet, but I wonder if a ground was damaged while removing the chasis for the chip upgrade? Other than the hum it works perfectly.

Ray McCarthy · From: New Hampshire, USA

I thought my 112 was humming louder than usual--turned out to be one of my cables.

Donny Hinson · From: Glen Burnie, Md. U.S.A.

Is the noise coming from the amp, or from the guitar?

Try this:

Without using your guitar, set the amp controls as you normally do and then turn the amp off. Now plug one end of your shortest cord (usually the one you use from steel to vol pedal) into the HIGH input, and then plug the other end of that cord into the LOW input, so you just have a loop going from one input jack to the other. Now turn on the amp...do you hear any hum? If not, your hum is coming from the guitar or pickup.

Dale Tiemessen · From: New Hampton,Ia. U.S.A.

The amp is plugged into a power conditioner,and still hums even with nothing plugged in.

Steven Finley · From: California, USA

I have had three of these amps they all Hum no
matter where you use them,even with power conditioners,even with nothing plugged into them,
so much for a high definition studio amp,ok for
live jobs,BAD for studio to much HUM.

John Limbach · From: Billings, Montana, USA

Ditto for my 112.

I pinned it down to the preamp section. With everything disconnected and the reverb set to 0, there is a slight but discernable white noise. Advancing the reverb introduces a hum. This may be environmental since there are multiple flourescent lights and two computers operating in the room.

The good news (for me) is that I'm using a ProFex II for premap and EQ and when I plug the output of the ProFex into the Pwr Amp Input on the 112, bypassing the 112's preamp, EQ, and Reverb, its absolutely silent.

So, for sure there is hum being generated internally in the 112's reverb.

The noise coming from the preamp is very low and may be internal or external. It's low enough to be a minor distraction at best, and 99% of the time I'm using the ProFex straight into the power amp section, so its not a problem.

Joseph Meditz · From: Sierra Vista, AZ

My N112 also has a little hum, enough to be annoying. I thought perhaps the filter caps may have been degraded. So, I replaced C17 and C18 with slightly larger ones, the stock ones being 3300 uF and 80 WVDC. Measuring at the output transistors, the saw tooth ripple went from about 100 mV p-p to 50 mV p-p. With the DMM on Vac I measured 22 mVac and 14 mVVac respectively. This resulted in an audible reduction in hum. Probably around 6 dB.

I would say the filter caps in the amp were OK. The new caps of course have increased inrush. On the other hand, I think they are a better choice than the stock ones because they have higher capacitance and temperature rating and, I think, adequate voltage rating.

I think it was worth it. However, it's significantly more difficult than changing the preamp chips, and the payoff isn't great. So, it's not for everyone.

Mouser Part #: 667-ECO-S1JA562DA
Manufacturer Part #:
ECO-S1JA562DA
Manufacturer:
Panasonic Electronic Components
Description: Aluminum Electrolytic Capacitors - Snap In 5600UF 63V ELECT TSHA

Don Christy · Posted 17 Apr 2012 7:37 pm

My 112 started to hum about a month ago. I unplugged the cables and it still hums. Next I tried to plug a cable in to each jack,one at a time to see if the hum would quit. When I plugged the cable in to the remote jack on the back of the amp, the amp did not hum as loud. I took the cable out of the jack and turned the amp off and back on and my hum disappeared.

I can't figure this one out. Shocked

Joseph Meditz · From: Sierra Vista, AZ

I've just increased the capacitance at the pre-amp PS. C19,20 and C11,12 are now 2200 uF and 100 uF respectively. This did reduce hum to a very tolerable level. (Sorry, but I didn't do any before and after measurements.) The amp is now more enjoyable.

However, eventually I will have to open the amp up again because I've introduced a problem. Around 50% of the time when I power it up the pre-amp PS latches and has no +15V as evidenced by the pilot LED being off.

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